Evolved Universal Terrestrial Radio Access (EUTRA) and Evolved Universal Terrestrial Radio Access Network (EUTRAN) for cellular mobile communication have been studied in the 3rd Generation Partnership Project (3GPP). The EUTRA and the EUTRAN are called Long term Evolution (LTE). In the LTE, a base station apparatus is called evolved NodeB (eNodeB), and a terminal apparatus is called User Equipment (UE). The LTE is a cellular communication system in which an area covered by the base station apparatus is arranged cellularly at multiple locations. A single base station apparatus may manage multiple cells.
In the 3GPP, Proximity Services (ProSe) are studied. The ProSe includes ProSe discovery and ProSe communication. The ProSe discovery is a process which uses the EUTRA so as to specify that one terminal apparatus is in proximity to the other terminal apparatus. The ProSe communication is communication between two terminal apparatuses in proximity to each other, which uses a EUTRAN communication path established between two terminal apparatuses. For example, the communication path may be directly established between the terminal apparatuses.
The ProSe discovery and the ProSe communication are respectively called D2D discovery and D2D communication. The D2D discovery and the D2D communication are collectively called D2D.
NPL 1 describes that a subset of resource blocks is reserved for the D2D, that a network configures a set of D2D resources, and that a terminal apparatus is permitted to transmit a D2D signal in the configured resource.